1. Field of the Invention
The present invention relates generally to digital communications and interface devices in computer systems. In particular, the present invention relates to a system and method for sending multiple data signals or streams over a serial line. Still more particularly, the present invention relates to a system and method for sending an isochronous data stream and one or more additional data streams over a serial link.
2. Description of the Background Art.
The use and proliferation of computers is well known. Recently, however, the use of computers for multimedia applications has drastically increased. Especially in the area of desktop computing, new multimedia applications (such as editing full motion video, still pictures, sound clips as well as other programs that combine audio input/output and video input/output) are demanding increasing computing power and bandwidth from interconnection resources. For example, a primary area where more bandwidth is needed is in the connection of computer systems to display devices. The standard resolution for graphics, even in the desktop environment, has dramatically increased the density of pixels as well as the number of colors and shades of gray. The bandwidth requirement for high resolution displays is extremely high, so high that typical interconnect systems are dedicated to refreshing the display data stream such that the entire data channel is available only to carry display video and control data. Furthermore, the blanking time required by certain display types (e.g. CRTs), makes a part of the available bandwidth not usable. Thus, there is a need for a digital communications interconnect structure that can provide the desired high speed and bandwidth.
A common approach to satisfying the increases in the required data transfer rates has been to increase the number of parallel lines used in interconnect structures. However, this approach has a number of shortcomings. First, increasing the number of parallel lines requires increased amounts of space for the interconnect structures such as connectors in addition to the increase in materials for signal lines and cables. Second, increasing the number of parallel lines increases the number of input/output pins for integrated circuits which further heightens an existing problem because of the computational capacity being added to such integrated circuits and the corresponding need for more input/output pins. Third, increasing the number of parallel lines and sending data at high speeds over such lines creates additional problems in the form of electromagnetic interference. Thus, the addition of more parallel signal lines cannot satisfy the need for additional bandwidth.
Therefore, there is a continuing need for a simple and reliable system and method for transmission of data at a high-speeds. This system and method should not require extensive hardware and be adaptable to a variety of different isochronous signals and data stream combinations that may need to be sent over a serial line.